A so-called build-up wiring board including wiring layers stacked alternately with insulating layers to be interconnected by via holes piercing through the insulating layers is known.
To manufacture such a wiring board, for example, wiring layers and insulating layers are stacked on a flat surface of a support, and thereafter, the support is removed. As a result, a surface of a wiring layer and a surface of an insulating layer that have been in contact with the support are exposed at the same flat surface. Next, the surface of the wiring layer that has been in contact with the support is etched to be roughened. Thereafter, a solder resist layer is formed to cover part of the roughened surface of the wiring layer to selectively expose the wiring layer. The surface of the wiring layer is roughened to increase adhesion between the wiring layer and the solder resist layer. (See, for example, Japanese Laid-open Patent Publication No. 2015-018976.)